Method and device for transmitting binary data

Abstract

A method for transmitting binary data using a M-ASK constellation divided into M/2 sets of two symbols is disclosed. Each set of index i comprises the i th and i th +M/2 symbols of the constellation and is associated with a probability pi of transmitting the first symbol of the set. First, m−1 bits are obtained from an equiprobable binary source where m=log 2 M. A binary source is then selected in a plurality of binary sources responsive to said m−1 bits, each binary source of index i being associated with a probability of outputting a bit zero equal to pi. A symbol of the M-ASK constellation is obtained that is associated with the binary word formed by the m−1 bits as less significant bits and a bit obtained from the selected source as most significant bit. The symbol is finally transmitted to a receiver over a communication channel.

The invention claimed is: 
     
       1. A method, in a transmitter, for transmitting binary data using a M-ASK (Amplitude-Shift Keying) constellation divided into M/2 sets of two symbols, each set of index i comprising the i th  and i th +M/2 symbols of the M-ASK constellation, where iϵ[1;M/2], and being associated with a probability p i  of transmitting the first symbol of the set and a probability 1−p i  of transmitting the second symbol of the set and wherein each symbol of the M-ASK constellation is associated with a binary word defined using natural labelling, said method comprising:
 a) obtaining m−1 bits from an equiprobable binary source where m=log 2 M; 
 b) selecting a binary source in a plurality of binary sources responsive to said m−1 bits, each binary source of index i being associated with a probability of outputting a bit zero equal to p i ; 
 c) obtaining one bit from the selected source; 
 d) obtaining a symbol of the M-ASK constellation associated with the binary word formed by the m−1 bits as less significant bits and the bit obtained from the selected source as most significant bit; 
 e) transmitting said obtained symbol to a receiver over a communication channel. 
 
     
     
       2. The method according to  claim 1 , wherein selecting the binary source in a plurality of binary sources responsive to said m−1 bits comprises—:
 determining a decimal value of a binary sequence formed by the m−1 bits; and 
 selecting the binary source whose index equal said decimal value incremented by one. 
 
     
     
       3. The method according to  claim 1  wherein the plurality of binary sources comprises 2 m−1  binary sources. 
     
     
       4. The method according to  claim 3 , wherein, 
       
         
           
             
               
                 
                   p 
                   i 
                 
                 = 
                 
                   1 
                   - 
                   
                     p 
                     
                       
                         M 
                         2 
                       
                       - 
                       i 
                       + 
                       1 
                     
                   
                 
               
               , 
               
                 1 
                 ≤ 
                 i 
                 ≤ 
                 
                   M 
                   4 
                 
               
               , 
             
           
         
       
       the plurality of binary sources is reduced to 2 m−2  binary sources and wherein selecting a binary source responsive to said m−1 bits comprises:
 determining a decimal value D of a binary sequence formed by the m−1 bits; and 
 selecting the binary source whose index equal M/2−D in the case where 
 
       
         
           
             
               
                 
                   
                     M 
                     4 
                   
                   + 
                   1 
                 
                 ≤ 
                 
                   D 
                   + 
                   1 
                 
                 ≤ 
                 
                   M 
                   2 
                 
               
               ; 
             
           
         
       
       and
 selecting the binary source whose index equal said decimal value incremented by one, otherwise; 
 
       and wherein, in the case where the binary source whose index equal M/2−D is selected, the bit obtained from the selected source is flipped before obtaining a symbol of the M-ASK constellation. 
     
     
       5. The method according to  claim 1 , wherein each binary source of index i in the plurality of binary sources is obtained from the equiprobable binary source by applying binary distribution matching on sequences of 
       
         
           
             
               
                 r 
                 
                   S 
                   ⁢ 
                   max 
                 
               
               ⁢ 
               
                 H 
                 ⁡ 
                 ( 
                 
                   p 
                   i 
                 
                 ) 
               
             
           
         
       
       bits, where S max  is the number of sources in the plurality of binary sources, H(p i ) denotes a binary entropy with probability p i  and r being an integer greater than or equal to 1. 
     
     
       6. The method according to  claim 1 , further comprising—:
 encoding r times (m−1)*k bits obtained from the equiprobable binary source using an error correcting code into (m−1)*n bits, where n and k are integers; 
 obtaining each binary source of index i in the plurality of binary sources from the equiprobable binary source by applying binary distribution matching on sequences of 
 
       
         
           
             
               
                 
                   r 
                   * 
                   n 
                 
                 
                   S 
                   ⁢ 
                   max 
                 
               
               ⁢ 
               
                 H 
                 ⁡ 
                 ( 
                 
                   p 
                   i 
                 
                 ) 
               
             
           
         
       
       bits obtained from the equiprobable binary source, where S max  is the number of sources in the plurality of binary sources and H(p i ) denotes the binary entropy with probability p i ; and
 applying a) to e) on each of the n sets of (m−1) bits—. 
 
     
     
       7. The method according to  claim 5 , further comprising obtaining the probabilities p i  from a table and transmitting to said receiver at least one index entry indicating the obtained probabilities. 
     
     
       8. The method according to  claim 5 , further comprising estimating the probabilities p i  from a predefined communication channel distribution and transmitting said estimated probabilities to said receiver. 
     
     
       9. The method according to  claim 5 , further comprising receiving the probabilities p i  from the receiver. 
     
     
       10. A transmitter configured to transmit binary data using a M-ASK (Amplitude-Shift Keying) constellation divided into M/2 sets of two symbols, each set of index i comprising the i th  and i th +M/2 symbols of the M-ASK constellation, where iϵ[1;M/2], and being associated with a probability p i  of transmitting the first symbol of the set and wherein each symbol of the M-ASK constellation is associated with a binary word defined using natural labelling, said transmitter comprising at least one processor configured to:
 a) obtain m−1 bits from an equiprobable binary source where m=log 2 M; 
 b) select a binary source in a plurality of binary sources responsive to said m−1 bits, each binary source of index i being associated with a probability of outputting a bit zero equal to p i ; 
 c) obtain one bit from the selected source; 
 d) obtain a symbol of the M-ASK constellation associated with the binary word formed by the m−1 bits as less significant bits and the bit obtained from the selected source as most significant bit; 
 e) transmit said obtained symbol to a receiver over a communication channel. 
 
     
     
       11. A non-transitory computer readable storage medium storing program code instructions, the program code instructions causing implementation of the method according to  claim 1  when the program code instructions are read from the non-transitory computer readable storage medium and run by a programmable device.